Aspects of environmental protection are becoming increasingly important on a global scale. An important aspect among those is the purification of wastewaters from households, industry and trade.
Such wastewaters may be polluted with diverse noxious materials. Accordingly, several different treatment methods are available, which in principle can be subdivided into mechanical, physical, biological and chemical methods. In connection with the treatment of water, especially wastewater, proposals already exist concerning the use of cavitation for destruction of noxious organic substances. The underlying concept is that the intense pressure pulsations occurring during cavitation and associated with extreme pressure peaks destroy organic substances or compounds or break them apart so that they can be extensively degraded with further treatment methods. Proposals to this effect, on using cavitation devices for purification of water, are described, for example, in WO 2007/076579 A1, EP 1780177 A2 and U.S. Pat. No. 6,224,826 B1.
Furthermore, the article of Martin Petkovsek et al. “Rotation Generator of Hydrodynamic Cavitation for Water Treatment” (Separation and Purification Technology, 2013) deals with the use of cavitation for removal of pharmaceutical resides from water. It proposes and investigates a cavitation device of the class in question according to the preamble of claim 1: This has two rotors, which are mounted in a housing, rotate coaxially in opposite directions and are equipped with projections disposed opposite one another and forming a slit. A water inlet and (disposed opposite) a water outlet open laterally into the housing. Influences of additives (hydrogen peroxide) and of process parameters (temperature) are illustrated in the publication. In one of the investigated embodiments, the end faces of the projections of one of the two rotors are chamfered in circumferential direction to the effect that the slit width relative to the projections of the second rotor is increased counter to the direction of rotation of the rotor in question.
EP 2228134 A2 discloses a device used for the treatment of liquid wherein cavitation effects are also used in connection with collection, purification and homogenization (e.g. with the objective of improving the combustion of a liquid fuel). The device comprises a flow-through housing provided with a liquid inlet and a liquid outlet, in which a disk (rotor) driven in rotation is disposed with axially oriented projections. The projections of the rotor are disposed on one or more circles. They are disposed opposite either the end wall of the housing or a second disk mounted therein and rotating in opposite direction, wherein axially oriented projections may be disposed on coaxial circles on the end wall of the housing or on the second disk. The projections of the rotor and the projections provided on the end wall of the housing or on the second disk overlap one another in axial direction and in addition are disposed in “gap-forming” manner, such that the projections of the rotor disposed on one circle respectively penetrate into an annular intermediate space that exists between two neighboring circles of projections of the end wall of the housing or of the second disk. The situation is analogous for the projections disposed on the end wall of the housing or on the second disk. The rotating second disk may then be mounted on a rotating pipe, which forms the liquid inlet.
Heretofore the cavitation of water in order to treat it has not been used on the industrial scale. Obviously no process has yet existed that can be used industrially under aspects of reliability, effectiveness or efficiency and other aspects of practical relevance.
The object of the present invention is to provide a cavitation device, which is appropriate for treatment of water by cavitation and which is suitable for industrial service, especially by the fact that efficient treatment of water by means of cavitation is possible on an industrial scale using the cavitation device.